Frame for color selection electrode assembly and method of manufacturing color selection electrode assembly

ABSTRACT

A frame ( 3 ) for supporting a color selection electrode body ( 2 ) under tension includes a pair of first frames ( 10 ) arranged in the horizontal direction and a pair of second frames ( 20 ) arranged in the vertical direction. The first frames ( 10 ) are each formed by bending a sheet material into a substantially triangular sectional shape, whose three side faces are formed by a first support part ( 12 ), a second support part ( 14 ) and a third support part ( 16 ). Projections ( 30 ) each having a shear plane ( 32 ) are formed in an inner position of the one side edge of the first support part ( 12 ). The other side edge ( 16   a )) of the third support part ( 16 ) is arranged to be in contact with a main surface of the first support part ( 12 ) and the shear plane ( 32 ) of each of the projections ( 30 ). Shearing force acting between the other side edge ( 16   a )) of the third support part ( 16 ) and first support part ( 12 ) is received by the projections ( 30 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a technique of securelysupporting an electrode used for color selection (hereinafter referredto as “color selection electrode”) in a cathode ray tube (CRT) to whichtension is applied in a predetermined direction, that is, a colorselection electrode body such as a tensioned shadow mask or aperturegrille.

[0003] 2. Description of the Background Art

[0004] Among conventional techniques of supporting a grid which is acolor selection electrode is a technique in which support members forsupporting a grid are formed in a substantially L-sectional shape andreinforcing plates are welded to the support members, so that thesupport members are formed in a hollow triangular sectional shape. Suchtechnique is disclosed in, e.g., Japanese Patent No. 3,218,667 (Document1).

[0005] Another technique is known in which two first members forsupporting a mask are formed in a hollow triangular sectional shape andare coupled to each other with solid rods or hollow pipes by theirrespective ends. Such technique is disclosed in, e.g., Japanese PatentApplication Laid-Open No. 9-167578 (1997) (Document 2).

[0006] Still another technique is known in which frame members areformed of a dual phase stainless steel of relatively high strength forreducing the thickness and weight of the frame members. Such techniqueis disclosed in, e.g., Japanese Patent Application Laid-Open No.9-249942 (1997).

[0007] Further, a technique in which a shadow mask is welded to externaledges of a mask frame is disclosed in, e.g., Japanese Patent ApplicationLaid-Open No. 2000-67748.

[0008] Furthermore, a technique is known in which a prescribed portionon one side face of each of triangular pipes for supporting a mask iscut away by three sides into a substantially U-shape and the prescribedportion is bent up to form a lip, so that the triangular pipe edge isclamped by the lip. Such technique is disclosed in, e.g., NationalPublication of Translation No. 2002-531919 (Document 3).

[0009] However, when forming frames for supporting a color selectionelectrode body in a hollow triangular sectional shape as described inDocuments 1 and 2, the tension of the color selection electrode bodycauses a shearing force to act upon a connected portion between anoblique face and a side face of each frame. To withstand this shearingforce, fillet welding by arc welding or the like needs to be performedon the connected portion between the oblique face and side face of eachframe over the entire length of each frame.

[0010] However, high-temperature and low-speed welding such as arcwelding arises a problem in that thermal strain causes straindeformation at portions of the frames by which the color selectionelectrode body is supported.

[0011] On the other hand, in Document 3, a prescribed portion on oneside face of a triangular pipe is cut away by three sides into asubstantially U-shape and the prescribed portion is bent up to form alip, which arises a problem in that the triangular pipe edge digs intothe lip under a high shearing force resulting from a high tension of thecolor selection electrode body, resulting in deformation of the lip.Thus, deformation of the triangular pipe due to the shearing forcecannot be prevented.

SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to provide a techniqueof obtaining a rigid frame with as short a weld length as possible.

[0013] A first aspect of the invention is directed to a frame for acolor selection electrode assembly for supporting a color selectionelectrode body under tension. The frame includes at least two supportparts joined together at a predetermined angle. At least one projectionhaving a convex surface and at least one shear plane is formed on one ofthe support parts. An edge of the other one of the support parts isarranged to be in contact with one main surface of the one of thesupport parts and the shear plane.

[0014] Since at least one projection having the convex surface and atleast one shear plane is formed on the one of the support parts and theedge of the other one of the support parts is arranged to be in contactwith one main surface of the one of the support parts and the shearplane, a force acting upon the one of the support parts is received bythe projection. Therefore, the frame can be rigidified with as short aweld length as possible.

[0015] Particularly since the edge of the other one of the support partsis in contact with the shear plane of the projection, the edge isunlikely to dig into the projection. Therefore, the frame cansufficiently be rigidified.

[0016] A second aspect of the invention is directed to a frame for acolor selection electrode assembly for supporting a color selectionelectrode body under tension. The frame includes a pair of first framesand a pair of second frames for holding the pair of first framessubstantially in parallel to each other with a predetermined spacetherebetween. The pair of first frames are each formed in asubstantially triangular sectional shape, each including a first supportpart having one side edge to which the color selection electrode body issecured, a second support part having one side edge connected to theother side edge of the first support part through a bend, and a thirdsupport part having one side edge connected to the other side edge ofthe second support part through a bend. At least one projection having aconvex surface and at least one shear plane is formed in an innerposition of the one side edge of the first support part, and the otherside edge of the third support part is arranged to be in contact with amain surface of the first support part and the shear plane.

[0017] Since at least one projection having the convex surface and atleast one shear plane is formed in the inner portion of the one sideedge of the first support part and the other side edge of the thirdsupport part is arranged to be in contact with the main surface of thefirst support part and the shear plane, a force acting upon the firstsupport part is received by the projection. Therefore, the frame can berigidified with as short a weld length as possible.

[0018] Particularly since the other side edge of the third support partis in contact with the shear plane of the projection, the other sideedge is unlikely to dig into the projection. Therefore, the frame cansufficiently be rigidified.

[0019] A third aspect of the invention is directed to a frame for acolor selection electrode assembly for supporting a color selectionelectrode body under tension. The frame includes a pair of first framesand a pair of second frames for holding the pair of first framessubstantially in parallel to each other with a predetermined spacetherebetween. The pair of first frames are each formed in asubstantially triangular sectional shape, each including a frame body ina substantially L-sectional shape having a first support part having oneside edge to which the color selection electrode body is secured and asecond support part having one side edge connected to the other sideedge of the first support part through a bend, and a third support partfor covering an open side of the frame body opposite to the bend. Atleast one first projection having a convex surface and at least oneshear plane is formed in an inner position of the one side edge of thefirst support part, while at least one second projection having a convexsurface and at least one shear plane is formed in an inner position ofthe other side edge of the second support part. The one side edge of thethird support part is arranged to be in contact with a main surface ofthe second support part and the shear plane of the second projection,while the other side edge of the third support part is arranged to be incontact with a main surface of the first support part and the shearplane of the first projection.

[0020] Since the one side edge of the third support part is arranged tobe in contact with the main surface of the second support part and theshear plan of the second projection, a force acting upon the secondsupport part is received by the second projection. Also, since the otherside edge of the third support part is in contact with the main surfaceof the first support part and the shear plane of the first projection, aforce acting upon the first support part is received by the firstprojection. Therefore, the frame can be rigidified with as short a weldlength as possible.

[0021] Further, it is not necessary to bend a sheet material at arelatively sharp angle, which allows the pair of first frames to bemanufactured with stable quality.

[0022] A fourth aspect of the invention is directed to a method ofmanufacturing a color selection electrode assembly. The method includesthe following steps (a) to (d). The step (a) is to form a pair of firstframes and a pair of second frames by pressing a sheet material. Thestep (b) is to join the pair of first frames and the pair of secondframes to form a rectangular frame. The step (c) is to secure a colorselection electrode body to the pair of first frames while pressing sidefaces of the pair of first frames in the direction that they approacheach other, and thereafter to release a pressure imposed on the pair offirst frames. The step (d) is to perform heat treatment for heating thepair of first frames and the pair of second frames at temperaturesranging from 450 to 500° C. after pressing in the step (a) and beforethe step (c).

[0023] Performing the pressing before the heat treatment can improvepress productivity. Also, performing the heat treatment after thepressing allows the frame to be rigidified.

[0024] These and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a perspective view of a color selection electrodeassembly according to a first preferred embodiment of the presentinvention;

[0026]FIGS. 2A to 2D each illustrate an example of a color selectionelectrode body;

[0027]FIGS. 3A to 3C each illustrate an example of a projection;

[0028]FIG. 4 is a cross-sectional schematic view of a first frameaccording to the first preferred embodiment;

[0029]FIG. 5 is a sectional view of a variant of the first frameaccording to the first preferred embodiment;

[0030]FIG. 6 is a perspective view of a color selection electrodeassembly according to a second preferred embodiment of the invention;

[0031]FIG. 7 is a cross-sectional schematic view of a first frameaccording to the second preferred embodiment;

[0032]FIG. 8 is a sectional view of the first frame according to avariant of the second preferred embodiment;

[0033]FIG. 9 is a perspective view of a color selection electrodeassembly frame according to a third preferred embodiment of theinvention;

[0034]FIG. 10 is a perspective view of a color selection electrodeassembly frame according to a fourth preferred embodiment of theinvention;

[0035]FIG. 11 is an explanatory schematic plan view of r a colorselection electrode assembly frame according to a fifth preferredembodiment of the invention;

[0036]FIG. 12 illustrates a curved shape of a first frame according tothe fifth preferred embodiment;

[0037]FIG. 13 is an explanatory schematic plan view of a frame accordingto a comparative example;

[0038]FIG. 14 is a perspective view of a color selection electrodeassembly frame according to a sixth preferred embodiment of theinvention;

[0039]FIG. 15 is a perspective view of a color selection electrodeassembly frame according to a seventh preferred embodiment of theinvention;

[0040]FIG. 16A is a perspective view of a color selection electrodeassembly frame according to an eighth preferred embodiment of theinvention, and FIG. 16B is a sectional view taken along the line A-A ofFIG. 16A;

[0041]FIG. 17 is a perspective view of a color selection electrodeassembly frame according to a ninth preferred embodiment of theinvention;

[0042]FIG. 18 is a perspective view of a color selection electrodeassembly frame according to a variant of the ninth preferred embodiment;

[0043]FIG. 19 is a perspective view of a color selection electrodeassembly frame according to a tenth preferred embodiment of theinvention;

[0044]FIG. 20 is a perspective view of a color selection electrodeassembly frame according to a variant of the tenth preferred embodiment;

[0045]FIG. 21A is an explanatory view of a secured part between a colorselection electrode body and a first frame according to an eleventhpreferred embodiment of the invention, and FIG. 21B is a partiallyenlarged view of FIG. 21A;

[0046]FIG. 22 is a sectional view of an essential part of a colorselection electrode assembly according to a twelfth preferred embodimentof the invention;

[0047]FIG. 23 is a sectional view of an essential part of a colorselection electrode assembly according to a comparative example;

[0048]FIGS. 24A and 24B each illustrate a sectional structure of a weldaccording to a thirteenth preferred embodiment of the invention; and

[0049]FIG. 25 is a flow chart of manufacturing steps of a colorselection electrode assembly according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] First Preferred Embodiment

[0051]FIG. 1 is a perspective view of a color selection electrodeassembly 1 according to a first preferred embodiment of the presentinvention.

[0052] The color selection electrode assembly 1 is one of components ofa color selection mechanism in a cathode ray tube (CRT) and includes acolor selection electrode assembly frame (hereinafter briefly referredto as “frame”) 3 and a color selection electrode body 2 stretched by theframe 3 under tension.

[0053] The color selection electrode body 2 is formed in a thin sheetwith a plurality of electron beam holes 2a. FIG. 1 shows only a partthat corresponds to substantially a half of a screen. The colorselection electrode body 2 is formed, for example, by perforating theelectron beam holes 2 a on a cold-rolled steel of 0.08 to 0.15 mmthickness by chemical etching.

[0054] For the color selection electrode body 2, the structure as shownin, for example, FIGS. 1 and 2A is employed in which the plurality ofelectron beam holes 2 a arranged in a plurality of columns in apredetermined direction (here, the vertical direction of the screen) aredivided by real bridges (real ties) 2 b.

[0055] Other examples are: a color selection electrode body 2B shown inFIG. 2B with the plurality of electron beam holes 2 a arranged in aplurality of columns in a predetermined direction being coupled to oneanother by the real bridges 2 b or dummy bridges (false ties) 2 c; and acolor selection electrode body 2C shown in FIG. 2C with the plurality ofelectron beam holes 2 a arranged in a plurality of columns in apredetermined direction being coupled to one another by the dummybridges 2 c. The real bridges 2 b are elements extending across theelectron beam holes 2 a in the widthwise direction thereof forcompletely separating the electron beam holes 2 a from one another. Thedummy bridges 2 c are elements projecting toward the inside of theelectron beam holes 2 a in the widthwise direction thereof and not beinginterconnected at the middle of the electron beam holes 2 a in thewidthwise direction thereof for incompletely separating the electronbeam holes 2 a from one another.

[0056] Still another example is a color selection electrode body 2Dshown in FIG. 2D with the electron beam holes 2 a arranged in aplurality of columns in a predetermined direction being formed in slitform without being separated by bridges from one ends to the other ends.The color selection electrode body 2 is not limited to these examples,but is applicable to all electrode bodies with electron beam holes 2 athat are supported under a certain degree of tension.

[0057] Referring back to FIG. 1, the frame 3 is intended for supportingthe color selection electrode body 2 under tension, and includes a pairof first frames 10 and a pair of second frames 20, which are coupled toeach other to form a substantially rectangular frame.

[0058] Holding members (e.g., holding parts and pin-fit-hole-openedsheet) for aligning the frame 3 with the inner surface of a CRT panel byholding its respective side faces or four corners are provided near theside faces or four corners, illustration of which is omitted here.

[0059] The pair of first frames 10 are formed in long lengths, and whenincorporated in a CRT, they are arranged to face each other in asubstantially horizontal direction with respect to the verticaldirection of the screen. The aforementioned color selection electrodebody 2 is secured to the first frames 10. The first frames 10 are alsocalled horizontal frames in general.

[0060] The first frames 10 each include a first support part 12 of along, narrow and substantially rectangular shape, a second support part14 of a long, narrow and substantially rectangular shape and a thirdsupport part 16 of a long, narrow and substantially rectangular shape.

[0061] The color selection electrode body 2 is secured to one side edge12 a which is one side long edge of the first support part 12. In thepresent embodiment, the one side edge 12 a has a substantially arc shapeas viewed in the direction of the normal to the first support part 12such that the color selection electrode body 2 is supported as a part ofthe periphery of a cylinder.

[0062] The other side edge which is the other side long edge of thefirst support part 12 is connected to one side edge which is one sidelong edge of the second support part 14 through a bend 13. The bendingangle of the bend 13 is approximately 90 degrees, for example. The otherside edge which is the other side long edge of the second support part14 is connected to one side edge which is one side long edge of thethird support part 16 through a bend 15. The bending angle of the bend15 is smaller than 90 degrees. Further, the other side edge 16 a whichis the other side long edge of the third support part 16 is arranged tobe in contact with a position on one main surface (inner surface) of thefirst support part 12 on the inner side of the one side edge 12 a. Inthe present embodiment, part of the third support part 16 near the otherside edge 16 a is formed as a flange 16 f slightly bent in such a manneras to come into surface contact with the one main surface of the firstsupport part 12.

[0063] The overall configuration of each of the first frames 10represents a hollow pipe of a substantially triangular sectional shapeformed by the first to third support parts 12, 14 and 16. When assembledinto the color selection electrode assembly 1, the first support part 12is held substantially vertically to the color selection electrode body2, and the second support part 14 is held to extend from the other sideedge of the first support part 12 toward the inside of the frame 3substantially in parallel to the color selection electrode body 2, andthe third support part 16 is held to extend transversely with respect tothe first and second support parts 12 and 14 while connecting the oneside edge 12 a of the first support part 12 and the other side edge ofthe second support part 14.

[0064] The first frames 10 are made of a steel sheet of a thicknesssuitable for sheet-metal press, and are formed, for example, by bendinga sheet.

[0065] Further, a plurality of projections 30 are provided toward theinside of the frame 3 at a position on the inner side of the one sideedge 12 a of the first support part 12, more specifically, along theline on which the other side edge 16 a of the third support part 16 isto be provided. The number of projections 30 may be at least one.

[0066] A projection 30 has a convex surface 31 and at least one shearplane 32 as shown in FIG. 3A. Specifically, a substantially rectangularregion on the first support part 12 is sheared by two sides which aresubstantially parallel to the other side edge 16 a of the third supportpart 16 and is punched to form the projection 30 in a substantiallypartial cylindrical shape. The projection 30 has a width B, a height Dand a projecting dimension D.

[0067] Another example is a projection 30B shown in FIG. 30B. Asubstantially semicircular region on the first support part 12 issheared by one side located adjacent to the other side edge 16 a of thethird support part 16 and is punched to form a substantiallyhemispherical shape. Still another example is a projection 30C shown inFIG. 3C. A substantially triangular region on the first support part 12is sheared by only one side located adjacent to the other side edge 16 aof the third support part 16 and is punched to form a triangularpyramid. In short, the projection 30 may be formed by concurrentlyperforming shearing and drawing, and may have one or more shear planesfacing the other side edge 16 a of the third support part 16.

[0068] The other side edge 16 a of the third support part 16 is arrangedto be in contact with one main surface of the first support part 12 aswell as the shear plane 32.

[0069] Further, in the present embodiment, the flange 16 f near theother side edge 16 a of the third support part 16 is in surface contactwith the first support part 12, and welding is conducted intermittentlyat welds 5 along the extending direction of the other side edge 16 a.

[0070] The pair of second frames 20 have a function of holding the pairof first frames 10 with a predetermined space therebetween substantiallyin parallel to each other. When incorporated in a CRT, the pair ofsecond frames 20 are provided at the left and right sides of a screen ina substantially vertical direction, which are called vertical frames.

[0071] Specifically, the second frames 20 are made of a steel sheet of athickness suitable for sheet-metal press, and each include a frame body22 of a long narrow box shape with one side opened and a cover 24attached to the opening of the frame body 22.

[0072] The frame body 22 is formed by, for example, bending a steelsheet into a substantially U-sectional shape, closing its both ends andwelding lap joints or edges of members constituting the respective sidefaces.

[0073] The cover 24 is provided for improving the bending strength ofthe second frames 20, and secured to the opening of the frame body 22 bywelding or the like.

[0074] In the present embodiment, for easy welding between the first andsecond frames 10 and 20 as will be described later, the cover 24 doesnot completely cover the opening of the frame body 22 such that the bothend portions of the opening of the frame body 22 remain open when thecover 24 is attached. That is, the cover 24 is attached to the openingof the frame body 22 so as to cover a portion except the both endportions of the opening of the frame body 22.

[0075] For the purpose of weight reduction, a steel sheet used for thepair of first frames 10 and pair of second frames 20 is preferably asthin as possible as the strength requirements permit. However, forwelding the color selection electrode body 2 with a stable strength, thelowest limit of the sheet thickness is preferably 0.7 mm. Whenconducting laser welding, for example, for achieving low distortion, theupper limit of the sheet thickness is preferably 1.8 mm (3.6 mm at a lapjoint) for the purpose of stably welding two sheets to their reversesides as well as achieving high productivity (welding speed and energy).

[0076] Further, at least one of the extending direction of the bends 13and 15 of each of the first frames 10 and that of the bends of each ofthe second frames 20 is preferably set to be substantially perpendicularto the rolling direction of a parent steel sheet of the frames.

[0077] That is, bending, by pressing or the like, a dual phase stainlesssteel sheet or precipitation hardening stainless steel sheet which isgenerally hard and elongates little is likely to cause cracks along thequarter grain in the rolling direction. This makes it necessary to takesome measures such as setting a bend to have a radius three times thesheet thickness or greater. In this case, a problem is likely to arisein that the sheet material cannot be bent with high accuracy.

[0078] Therefore, the first and second frames 10 and 20 are formed bybending with the rolling direction being set as hollow arrows shown inFIG. 1, which can prevent cracks only by setting the bend to have aradius approximately 1.2 times to twice the sheet thickness. Thus, thefirst and second frames 10 and 20 can be obtained with a bending angleof high accuracy.

[0079] When assembling the pair of first frames 10 and pair of secondframes 20 in a substantially rectangular frame, lap welding is carriedout through the openings adjacent to the cover 24 in the state which thesecond support part 14 of each of the first frames 10 being overlappedwith corresponding end portions of the second frames 20 opposite to theopenings adjacent to the cover 24. Here, welding is carried out at welds5 c of a substantially rectangular shape. Such welding is performed atthe four corners, whereby the frame 3 of a substantially rectangularshape is assembled.

[0080] Further, a pair of opposite sides of the color selectionelectrode body 2 are secured to the one side edge 12 a of each of thefirst support parts 12 by welding or the like. When securing, the pairof first frames 10 are subjected to such force that causes elasticdeformation in the direction that the first frames 10 approach eachother. After securing, such force is released, when a force that thefirst frames 10 tend to return to their original positions applies aload to the color selection electrode body 2 that pulls the colorselection electrode body 2 outwardly with respect to the frame 3 in thedirection substantially perpendicular to the longitudinal direction ofthe pair of first frames 10.

[0081] The operation of the color selection electrode assembly 1 of theaforementioned structure will be described.

[0082]FIG. 4 is a cross-sectional schematic view of the first frame 10.In this drawing, a reaction force with respect to the tension applied tothe color selection electrode body 2 is represented by vector T.

[0083] In this case, the other side edge 16 a of the third support part16 is in surface contact with one main surface of the first support part12 while the flange 16 f near the other side edge 16 a is welded to thefirst support part 12. A transverse vector P of the reaction force Tcorresponding to the widthwise direction of the third support part 16acts upon the third support part 16.

[0084] On the other hand, the second frames 20 are respectively attachedto the both ends of the first frame 10, and a force in the directionthat the second frames 20 approach each other acts upon the first frame10. Then, provided that the middle portion of each of the second frames20 in the longitudinal direction is a secured end (hatched part in FIG.4), a reaction force R acts upon a part of the third support part 16 ofthe first frame 10 connected to the second support part 14, consideringsymmetric conditions of load.

[0085] Therefore, a shearing force resulting from a vertical componentSP of the force P and the vertical component SR of the force R acts uponthe weld 5. However, the other side edge 16 a of the third support part16 is in contact with the shear plane 32 of the projection 30, which isthus prevented from moving upward. This can substantially control ashearing stress acting upon the weld 5.

[0086] In the above-described color selection electrode assembly 1, theother side edge 16 a of the third support part 16 is arranged to be incontact with one main surface of the first support part 12 and the shearplane 32 of the projection 30, which causes the above-mentioned shearingforce to be received by the projection 30. This allows rigidification ofthe frame 3 with the welds 5 provided intermittently, that is, with asshort a weld length as possible, without welding the other side edge 16a of the third support part 16 and the first support part 12 over theentire length of each of the first frames 10.

[0087] Particularly since the other side edge 16 a of the third supportpart 16 is in contact with the shear plane 32 of the projection 30, theother side edge 16 a is unlikely to dig into the projection 30 evenunder an excessively great shearing force, which allows the frame 3 tobe sufficiently rigidified.

[0088] In the present embodiment, although lap welding is carried outfor each of the first frames 10 with the flange 16 f of the thirdsupport part 16 and the first support part 12 being overlapped with eachother, the flange 16 f may be omitted and the edge of a contact portionbetween the other side edge 16 a of the third support part 16 and thefirst support part 12 may be welded at a weld 5 d.

[0089] Second Preferred Embodiment

[0090]FIG. 6 is a perspective view of a color selection electrodeassembly 101 according to a second preferred embodiment of theinvention. Components similar to those of the color selection electrodeassembly 1 according to the first preferred embodiment are representedby the same reference characters, explanation of which is thus omittedhere, and dissimilar points will be described particularly.

[0091] The color selection electrode assembly 101 includes a colorselection electrode assembly frame (hereinafter briefly referred to as“frame”) 103 and the color selection electrode body 2 stretched by theframe 103 under tension.

[0092] The frame 103 is intended for supporting the color selectionelectrode body 2 under tension, and includes a pair of first frames 110and the pair of second frames 20 which are coupled to each other to forma substantially rectangular frame.

[0093] The pair of first frames 10 are formed of a steel sheet of athickness suitable for sheet-metal press, and each have a frame body 111of a substantially L-sectional shape and a third support part 116.

[0094] The frame body 111 includes a first support part 112 of a long,narrow and substantially rectangular shape and a second support part 114of a long, narrow and substantially rectangular shape.

[0095] The color selection electrode body 2 is secured to one side edge112 a which is one side long edge of the first support part 112. In thepresent embodiment, the one side edge 112 a has a substantially arcshape as viewed in the direction of the normal to the first support part112 such that the color selection electrode body 2 is supported as apart of the periphery of a cylinder.

[0096] The other side edge which is the other side long edge of thefirst support part 112 is connected to one side edge which is one sidelong edge of the second support part 114 through a bend 113. The bendingangle of the bend 113 is approximately 90 degrees, for example.

[0097] The frame body 111 is formed by bending a sheet material into asubstantially L shape. For the same reasons as described in the firstpreferred embodiment, the extending direction of the bend 113 ispreferably set to be substantially perpendicular to the rollingdirection of a parent sheet material (i.e., the direction indicated byhollow arrows in FIG. 6).

[0098] The third support part 116 is formed in a long, narrow andsubstantially rectangular shape and is attached to the frame body 111 soas to cover an open side of the frame body 111 opposite to the bend 113.

[0099] Further, a plurality of projections 130 a are provided inside thefirst frame 110 at a position on the inner side of the one side edge 112a of the first support part 112, more specifically, along the line onwhich the other side edge 116 a of the third support part 116 isprovided.

[0100] A plurality of projections 130 b are also provided inside thefirst frame 110 at a position on the inner side of the other side edge114 a of the second support part 114, more specifically, along the lineon which the one side edge 116 b of the third support part 116 isprovided.

[0101] The number of projections 130 a and 130 b may be at least oneeach.

[0102] The projections 130 a and 130 b each have a similar configurationas the projections 30 or their variant described in the first preferredembodiment.

[0103] The other side edge 116 a of the third support part 116 isarranged to be in contact with one main surface (inner surface) of thefirst support part 112 as well as a shear plane of each of theprojections 130 a. Also, the one side edge 116 b of the third supportpart 116 is arranged to be in contact with one main surface (innersurface) of the second support part 114 as well as a shear plane of eachof the projections 130 b.

[0104] Further, in the present embodiment, a flange 116 af near theother side edge 116 a of the third support part 116 is in surfacecontact with the first support part 112, and at the long lapped portion,welding is conducted intermittently at welds 115 a along the extendingdirection of the other side edge 116 a. Similarly, a flange 116 bf nearthe one side edge 116 b of the third support part 116 is in surfacecontact with the second support part 114, and at the long overlappedportion, welding is conducted intermittently at welds 115 b along theextending direction of the one side edge 116 b.

[0105] The overall configuration of each of the first frames 110represents a hollow pipe of a substantially triangular sectional shapewith three side walls of the first, second and third support parts 112,114 and 116. When assembled into the color selection electrode assembly101, the first support part 112 is held substantially vertically to thecolor selection electrode body 2, and the second support part 114 isheld substantially in parallel to the color selection electrode body 2,extending toward the inside of the frame 103 with respect to the otherside edge of the first support part 112, and the third support part 116is held to extend transversely with respect to the first and secondsupport parts 112 and 114 while connecting the one side edge 112 a ofthe first support part 112 and the other side edge 114 a of the secondsupport part 114.

[0106] The pair of first frames 10 and the pair of second frames 20 arejoined to each other as described in the first preferred embodiment, andare assembled into the frame 103. Then, as in the first preferredembodiment, the color selection electrode body 2 is secured to the frame103.

[0107] The operation of the color selection electrode assembly 101 ofthe aforementioned structure will be described.

[0108]FIG. 7 is a cross-sectional schematic view of the first frame 110.In this drawing, a reaction force with respect to the tension applied tothe color selection electrode body 2 is represented by vector T.

[0109] In this case, as in the first preferred embodiment, a shearingforce resulting from a vertical component SP of the force P and thevertical component SR of the force R acts upon the weld 115 a betweenthe other side edge 116 a of the third support part 116 and the firstsupport part 112. However, the other side edge 116 a is in contact withthe shear plane of the projection 130 a, which is thus prevented frommoving upward. This can substantially control the shearing stress actingupon the weld 1154 a.

[0110] Likewise, a shearing force acts upon the weld 115 b between theone side edge 116 b of the third support part 116 and the second supportpart 114. However, the one side edge 116 b is in contact with the shearplane of the projection 130 b, which is thus prevented from movingupward. This can substantially control the shearing stress acting uponthe weld 115 b.

[0111] In the above-described color selection electrode assembly 101,the other side edge 116 a of the third support part 116 is arranged tobe in contact with one main surface of the first support part 112 andthe shear plane of the projection 130 a, which causes theabove-mentioned shearing force to be received by the projection 130 a.This allows rigidification of the first frames 110 with the welds 115 aprovided intermittently, that is, with as short a weld length aspossible, without welding the other side edge 116 a of the third supportpart 116 and the first support part 112 over the entire length of eachof the first frames 110.

[0112] Likewise, the one side edge 116 b of the third support part 116is arranged to be in contact with the main surface of the first supportpart 112 and the shear plane of the projection 130 b, which causes theabove-mentioned shearing force to be received by the projection 130 b.This allows rigidification of the first frames 110 with the welds 115 bprovided intermittently, that is, with as short a weld length aspossible, without welding the one side edge 116 b of the third supportpart 116 and the second support part 114 over the entire length of eachof the first frames 110.

[0113] Particularly in the present embodiment, since a sheet material isnot required to be bent at a relatively sharp angle, the problem ofcontrol of cracks and spring back can be prevented because of a slightincrease in the number of components caused by forming the third supportpart 116 of a different material and an increase in welds by thepresence of the welds 115 b, which results in an advantage in that thefirst frames 110 can be manufactured with stable quality.

[0114] In other words, in the first preferred embodiment, when thesecond support part 14 and third support part 16 are bent at a sharpangle (particularly when the radius of the bend is smaller than thesheet thickness), cracks occur. Further, in the first preferredembodiment, control of spring back is necessary in order to reliablybring the flange 16 f into surface contact with the first support part12 for achieving stable welding at the weld 5.

[0115] On the other hand, in the present embodiment, a sheet material isnot required to be bent at a relatively small angle, i.e., a sharpangle, which solves the above-described problem.

[0116] In the present embodiment, although lap welding is carried outwith the flange 116 af of the third support part 116 and the firstsupport part 112 being overlapped with each other and the flange 116 bfand the second support part 114 being overlapped with each other, theflanges 116 af and 116 bf may be omitted and the edge of a contactportion between the other side edge 116 a and the first support part 112and the edge of a contact portion between the one side edge 116 b andthe second support part 114 may be welded at weld 115 c, as shown inFIG. 8.

[0117] Third Preferred Embodiment

[0118]FIG. 9 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Baccording to a third preferred embodiment of the invention. Componentssimilar to those of the color selection electrode assembly 101 accordingto the second preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0119] In this frame 103B, at least part of each third support part 116Bwhich corresponds to the third support part 116 has a higher mechanicalstrength than the first and second support parts 112 and 114. Themechanical strength here refers to difficulty in deformation that iscapable of withstanding compressive loads caused by the load P andreaction force R, which is evaluated, for example, by modulus ofrigidity or the like.

[0120] Providing at least part of the third support part 116B with ahigh mechanical strength as described above is achieved by increasingthe thickness of the part or forming the part of a sheet material havinga high mechanical strength.

[0121] In the present embodiment, the third support part 116B is dividedinto a middle support part 116Bm and a pair of end support parts 116Beprovided on the both ends. The pair of end support parts 116Be have agreater thickness than the middle support part 116Bm. The difference inthickness causes the end support parts 116Be to have a higher mechanicalstrength than the middle support part 116Bm. The end support parts 116Beand middle support part 116Bm may be formed of different steel sheets sothat the former may have a higher mechanical strength than the latter.The middle support part 116Bm is formed of a sheet material of the samequality and thickness as the frame body 111, and thus, the end supportparts 116Be have a higher mechanical strength than the frame body 111.

[0122] The border between the end support parts 116Be and middle supportpart 116Bm may be joined or may not be joined to each other.

[0123] As described, the reason why the end support parts 116Be have ahigher mechanical strength than the middle support part 116Bm is that,when the color selection electrode body 2 is supported by the firstframes 110B under tension, the tension of the color selection electrodebody 2 is generally maximized at the respective ends of the first frames110B.

[0124] However, which part of the first frames 110B is to be maximizedin mechanical strength is determined by tension distributions of thecolor selection electrode body 2.

[0125] Further, it is needless to say that the third support part 116Bmay have a higher mechanical strength than the frame body 111 over itsentire length.

[0126] According to the color selection electrode assembly of thepresent embodiment, at least part of the third support part 116B has ahigher mechanical strength than the first and second support parts 112and 114, which allows the first frames 110B to be rigidified more.Further, the first and second support parts 112 and 114 may be formed ofa steel sheet relatively easy to deform, which thus have a highflexibility. Furthermore, the first and second support parts 112 and 114may be formed of a relatively thin sheet material, which contributes toweight reduction.

[0127] Fourth Preferred Embodiment

[0128]FIG. 10 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Caccording to a fourth preferred embodiment of the invention. Componentssimilar to those of the color selection electrode assembly 101 accordingto the second preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0129] In this frame 103C, each second support part 114C whichcorresponds to the aforementioned second support part 114 has a width Weat its both ends greater than a width Wc at the middle in itslongitudinal direction. Particularly, in the present embodiment, theother side edge 114Cb of the second support part 114C is formed toproject outwardly so that the second support part 114C has widenedportions at the both ends.

[0130] Also, a flange 116Cf near one side edge 116Cb of a third supportpart 116C which corresponds to the third support part 116 is widened atthe both ends as compared to the middle in its longitudinal direction.Therefore, the flange 116Cf is in contact with the second support part114C by a greater area at the both ends in its longitudinal direction ascompared to the middle of the first frame 110C in its longitudinaldirection, which means a greater number of welds are present at the bothends of each of the first frames 110C.

[0131] According to the color selection electrode assembly of thepresent embodiment, the second support part 114C is widened at the bothends of the first frame 110C, which allows the contact area of thesecond support part 114C and each of the second frames 20 to beincreased. This can increase the joining strength of the first frames110C and second frames 20. Particularly when the tension of the colorselection electrode body 2 is greater at the both ends of the firstframes 110C than at the middle in the longitudinal direction, thestructure is effectively capable of withstanding the tension.

[0132] Fifth Preferred Embodiment

[0133]FIG. 11 is an explanatory view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Daccording to a fifth preferred embodiment of the invention as viewedfrom the side of the stretched surface of the color selection electrodebody 2. Components similar to those of the color selection electrodeassembly 101 according to the second preferred embodiment arerepresented by the same reference characters, explanation of which isthus omitted here, and dissimilar points will be described particularly.

[0134] In this frame 103D, each first support part 112D whichcorresponds to the first support part 112 is curved with a radius ofcurvature Ry expanding opposite to the direction that the tension of thecolor selection electrode body 2 will work, i.e., outwardly from thecenter of a screen, in the state which the tension of the colorselection electrode body 2 is not yet applied. Also, the edge of eachsecond support part 114D connected to the first support part 112D iscurved in line with the curve of the first support part 112D.

[0135] Among methods of providing first frames 110D with the radius ofcurvature Ry is the use of welding strain, for example.

[0136] That is, when welding each third support part 116D to each framebody 111D, welding from the side of each third support part 116D causeseach first frame 110D of a substantially straight shape as indicated bybroken lines in FIG. 12 to be curved with the radius of curvature Ry asindicated by solid lines. This is caused by the phenomenon in which ametallic constitution of a weld is melted and then shrinks throughcooling. Welding performed from the side of each third support part 116Dcauses each third support part 116D to be curved so as to expandoutwardly. Particularly, increasing a welding load by extending thetotal length of welds provided intermittently in the longitudinaldirection of the first frames 110D or by performing welding in two linessubstantially in parallel to each other allows the radius of curvatureRy to be reduced. On the contrary, when the radius of curvature Ry is tobe increased, a welding load may be reduced or welding with a heat loadof the same degree may be performed from the opposite side of each thirdsupport part 116D.

[0137] Then, the color selection electrode body 2 is secured to the pairof first frames 110D while pressing the first frames 110D in thedirection that they approach each other. The color selection electrodebody 2 is thereby supported between the pair of first frames 110D undera predetermined degree of tension.

[0138] At this time, the pair of first frames 110D are pulled by thecolor selection electrode body 2 in the direction that the first frames110D approach each other, so as to substantially straighten up asindicated by broken lines in FIG. 11.

[0139] Thus, in the state which the color selection electrode body 2 issupported under tension, the degree of inward curvature of each firstsupport part 112D can be reduced, allowing electron beams not tointerference the first frames 110D, so that a manufacturing margin canbe improved.

[0140] This will be described below more specifically.

[0141]FIG. 11 shows an outer orbit 150 of electron beams indicated bydash-dot lines in the state which the color selection electrode assemblyaccording to the present embodiment is incorporated into a CRT. Here,the orbit 150 is an orbit as viewed in the direction of the normal tothe second support parts 114D of the first frames 110D.

[0142] On the other hand, FIG. 13 shows, by way of comparative example,an outer orbit 50 of electron beams indicated by dash-dot lines in thestate which the color selection electrode assembly 1 according to thefirst preferred embodiment is incorporated into a CRT.

[0143] In the both cases shown in FIGS. 11 and 13, when the colorselection electrode body 2 is supported under tension, the first frames10 and 110D are subjected to a force indicated by hollow arrows in therespective drawings resulting from the tension of the color selectionelectrode body 2, and are respectively deformed into the shapesindicated by broken lines in the respective drawings. That is, the firstframes 110D of the present embodiment substantially straighten up asshown in FIG. 11 while the first frames 10 of the first preferredembodiment are deformed into a curved shape which expand inwardly.

[0144] As is apparent from these drawings, a margin ΔY defined by thespace between the orbit 150 of electron beams and the first frames 110Dof the present embodiment shown in FIG. 11 is greater than that in thefirst preferred embodiment shown in FIG. 13. Therefore, the colorselection electrode assembly according to the present embodimentprovides a greater manufacturing margin from the viewpoint of preventingelectron beams from being shadowed by the first frames 110D, whichresults in a great advantage.

[0145] The description of the present embodiment is applicable to theother preferred embodiments including the first preferred embodiment.

[0146] Sixth Preferred Embodiment

[0147]FIG. 14 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 3E accordingto a sixth preferred embodiment of the invention. Components similar tothose of the color selection electrode assembly 1 according to the firstpreferred embodiment are represented by the same reference characters,explanation of which is thus omitted here, and dissimilar points will bedescribed particularly.

[0148] In the frame 3E, holding members 55E are attached to therespective ends of the first frames 10.

[0149] The holding members 55E are curved along the periphery of thebottom of the first frames 10 of substantially triangular sectionalshape. That is, the holding members 55E are each formed by bending astrip sheet of a predetermined width, and each include a curved holdingpart 56E along the outline of the bend 13 between the first and secondsupport parts 12 and 14 and a curved holding part 57E along the outlineof the bend 15 between the second and third support parts 14 and 16.

[0150] The holding members 55E are fit over and joined to the respectiveends of the first frames 10 by welds 5Ed.

[0151] According to this color selection electrode assembly, the holdingmembers 55E each hold the bend 13 between the first and second supportparts 12 and 14 as well as the bend 15 between the second and thirdsupport parts 14 and 16. This can reduce stresses imposed on therespective ends of the first frames 10 when a compressive load caused bythe load P resulting from the tension T and reaction force R act uponeach of the third support parts 16 as shown in FIG. 4. Therefore, thefirst frames 10 can be rigidified.

[0152] The description of the present embodiment is applicable to theother preferred embodiments including the second preferred embodiment.For instance, when applied to the second preferred embodiment, theholding members 55E may each have a holding part in agreement with theshape of the contact portion between each of the second and thirdsupport parts 114 and 116.

[0153] Seventh Preferred Embodiment

[0154]FIG. 15 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 3F accordingto a seventh preferred embodiment of the invention. Components similarto those of the color selection electrode assembly 1 according to thefirst preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0155] In this frame 3F, a pair of first frames 10F which correspond tothe first frames 10 of the first preferred embodiment have a highermechanical strength at their respective end portions than at theirmiddle portions. The mechanical strength here refers to difficulty indeformation that is capable of withstanding the tension of the colorselection electrode body 2.

[0156] In the present embodiment, respective end portions 10Fe of eachof the first frames 10F are greater in thickness than a middle portion10Fm. To form such first frames 10F, a sheet is prepared by joiningsheet materials (steel, alloy steel) of different thickness adjacentlyand in parallel to each other by laser welding or the like and pressingthe obtained sheet. This kind of structure is also called tailoredblank, which is generally used in sheet-metal press for car bodies aswell.

[0157] Instead of joining sheet materials of different thickness, sheetmaterials of different mechanical strength (steel, alloy steel) may bejoined adjacently and in parallel to each other.

[0158] According to this color selection electrode assembly, theportions where a relatively great tension is applied by the colorselection electrode body 2 are made mechanically strong, which allowsthe frame 3F to be rigidified.

[0159] Particularly, in an assembly where the end portions 10Fe of thefirst frames 10F have a higher mechanical strength by thickening, onlyportions that correspond to the end portions 10Fe need to be thickenedand the first frames 10F is not required to be thickened as a whole,resulting in an advantage of achieving both of weight reduction andrigidification.

[0160] The description of the present embodiment is applicable to theother preferred embodiments including the second preferred embodiment.For instance, when applied to the second preferred embodiment, the framebody 111 of each of the first frames 110 may be made mechanically strongat the both end portions than at the middle portion.

[0161] Eighth Preferred Embodiment

[0162]FIG. 16A is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Gaccording to an eighth preferred embodiment, and FIG. 16B is a sectionalview taken along the line A-A of FIG. 16A. Components similar to thoseof the color selection electrode assembly 101 according to the secondpreferred embodiment are represented by the same reference characters,explanation of which is thus omitted here, and dissimilar points will bedescribed particularly.

[0163] In this frame 103G, third support parts 116G which correspond tothe third support parts 116 each have beads 160G extending in theirwidthwise direction.

[0164] The beads 160G are each formed by pressing a sheet material intoa long narrow projection toward one side main surface (outer surface) orthe other side main surface (inner surface) of each of the third supportparts 116G. In the present embodiment, the beads 160G are formed inthree lines at regular intervals at the respective end portions of eachof the third support parts 116G where the tension of the color selectionelectrode body 2 tends to be particularly great. This achieves anassembly that copes with buckling deformation of the third support parts116G in their widthwise direction.

[0165] Of course, the beads 160G may be provided at the middle portionsof the third support parts 160G in their longitudinal direction. Theposition and the number of the beads 160G and the like are appropriatelyadjusted in accordance with the tension distributions of the colorselection electrode body 2.

[0166] According to the above-described color selection electrodeassembly, the third support parts 116G have a great strength againstbuckling deformation in their widthwise direction. Therefore, even witha compressive load resulting from the load P and reaction force R causedby the tension of the color selection electrode body 2 being applied,the third support parts 116G are unlikely to present bucklingdeformation, allowing the first frames 110G to be rigidified.

[0167] The description of the present embodiment is applicable to theother preferred embodiments including the first preferred embodiment.For instance, when applied to the first preferred embodiment, the beads160G may be provided at appropriate positions on the third support parts12 of the first frames 10.

[0168] Ninth Preferred Embodiment

[0169]FIG. 17 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Haccording to a ninth preferred embodiment of the invention. Componentssimilar to those of the color selection electrode assembly 101 accordingto the second preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0170] In this frame 103H, third support parts 116H which correspond tothe third support parts 116 of the second preferred embodiment are eachprovided with sheet-like reinforcing members 165H.

[0171] The reinforcing members 165H are each formed as a sheet extendingperpendicularly to each third support part 116H and in the widthwisedirection of each third support part 116H.

[0172] In the present embodiment, the reinforcing members 165H areprovided on the respective ends of each third support part 116H. To formsuch reinforcing members 165H, the respective ends of each third supportpart 116H are extended outwardly and the extended portions are bent at asubstantially right angle.

[0173] The reinforcing members 165H provide the third support parts 116Hwith a great strength against buckling deformation in their widthwisedirection. Therefore, even with a compressive load resulting from theload P and reaction force R resulting from the tension of the colorselection electrode body 2, the third support parts 116H are unlikely topresent buckling deformation, allowing the first frames 110H to berigidified.

[0174] In a frame 1031 shown in FIG. 18A as a variant, third supportparts 1161 which correspond to the third support parts 116 of the secondpreferred embodiment may each be divided into three in theirlongitudinal direction, i.e., end support parts 116Ie at the both endsand a middle support part 116Im at the middle, and reinforcing members1651 similar to the reinforcing members 165H may be formed at therespective ends of the support parts 116Ie and 116Im. The bordersbetween the end support parts 116Ie and the middle support part 116Immay or may not be welded together.

[0175] Instead of bending the respective ends of the third support parts116H or support parts 116I1e and 116Im, a reinforcing member 165J shownin FIG. 18B may be secured to each end of the third support parts 116.

[0176]FIG. 18B shows the reinforcing member 165J formed by bending asheet material into a substantially L shape, i.e., as a pair of sheetmembers 165Ja and 165Jb of a substantially rectangular shape formedintegrally to present a substantially L-sectional shape. Overlapping thesheet member 165Ja of the reinforcing member 165J with each end of thethird support parts 116 and welding together also allows the thirdsupport parts 116 to be reinforced.

[0177] The description of the present embodiment is applicable to theother preferred embodiments.

[0178] Tenth Preferred Embodiment

[0179]FIG. 19 is a perspective view of a color selection electrodeassembly frame (hereinafter briefly referred to as “frame”) 103Kaccording to a tenth preferred embodiment of the invention. Componentssimilar to those of the color selection electrode assembly 101 accordingto the second preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0180] In this color selection electrode assembly, connecting members170K are provided at the respective connecting portions between thefirst frames 110 and second frames 20 for supporting their connection.

[0181] The connecting members 170K are each formed by a first joint part172K to be joined to each of the first frames 110 and a second jointpart 174K to be joined to each of the second frames 20.

[0182] In the present embodiment, in each of the connecting members170K, the first joint part 172K of a substantially rectangular sheet andthe second joint part 174K of a substantially rectangular sheet formedintegrally into a substantially L shape. The connecting members 170K areeach formed by bending a sheet material into a substantially L shape.

[0183] The connecting members 170K are provided at the respectiveconnecting portions between the first frames 110 and second frames 20where their outer surfaces substantially intersect each other. That is,the first joint part 172K is joined to the outer surface of each of thesecond support parts 114 near the both ends by a weld, and the secondjoint part 174K is joined to the outer surface of sidewalls of each ofthe second frames 20 near the respective ends by a weld 173K.

[0184] According to this color selection electrode assembly, theconnecting members 170K maintain connection between the first frames 110and second frames 20 more reliably. Therefore, the strength of the frame103K is improved, so that even when a high stress resulting from thetension of the color selection electrode body 2 acts upon the frame103K, the frame 103K can sufficiently withstand such stress.Particularly, this brings an advantage of increasing the strength of theframe 103K without the need to thicken sheet materials for the firstframes 110 and second frames 20 or without causing weight increase.

[0185] Although described as being formed separately from the firstframes 110 and second frames 20, the connecting members 170K may beintegrally formed with the first frames 110 or second frames 20.

[0186] For instance, in a frame 103L shown in FIG. 20 as a variant, thesidewalls of the respective end portions of the second frames 20L areextended along the corresponding side faces of the first frames 110 toform connecting portions 170L. The connecting portions 170L are eachjoined to the corresponding side faces of the first frames 110 by, forexample, welds 171L.

[0187] The description of the present embodiment is applicable to theother preferred embodiments.

[0188] Eleventh Preferred Embodiment

[0189]FIG. 21A is an explanatory view of a secured part between thecolor selection electrode body 2 and each of the first frames 110according to an eleventh preferred embodiment of the invention, and FIG.21B is a partially enlarged view of FIG. 21A. In FIG. 21A, the firstframe 110 is in a position indicated by broken lines before supportingthe color selection electrode body 2 under tension, and moves to aposition indicated by solid lines when supporting the color selectionelectrode body 2 under tension. Components similar to those of the colorselection electrode assembly 101 according to the second preferredembodiment are represented by the same reference characters, explanationof which is thus omitted here, and dissimilar points will be describedparticularly.

[0190] The present embodiment is directed to the securing of the colorselection electrode body 2 and first frames 110.

[0191] The color selection electrode body 2 is secured to the firstframes 110 by the following basic steps. That is, the color selectionelectrode body 2 is held by its periphery and pressed against the oneside edge 112 a of the first support part 112. At the same time, thepair of first frames 110 are pressed in the direction that they approacheach other. In this state, a welding electrode 175 is pressed onto thecolor selection electrode body 2 at a contact portion between the colorselection electrode body 2 and the one side edge 112 a for securing thecolor selection electrode body 2 to the one side edge 112 a by seamwelding or the like. Thereafter, the periphery of the color selectionelectrode body 2 is removed, whereby the securing of the color selectionelectrode body 2 is completed.

[0192] Here, a sheet material of a predetermined shape to be an originalof the first frames 110 is formed by press-shearing of a parent sheetmaterial into the predetermined shape. Therefore, the one side edge 112a of the first support part 112 has a first end-face region S includinga shear drop and a shear plane formed by press-shearing and a secondend-face region B including a fracture surface. A shear drop is a freesurface depressed by a shearing lip biting into a material until momentbefore shearing phenomenon occurs. A shear plane is a surface formed bythe shearing phenomenon. A fracture surface is a rough surfacecontaining cracks.

[0193] In the present embodiment, the first end-face region S isarranged on the outer side of the frame 103 with respect to the secondend-face region B. Then, the color selection electrode body 2 is securedto the first end face region S, more specifically, to the top of thefirst end-face region S (see the mark X in FIG. 21B).

[0194] Since the color selection electrode body 2 is secured to thefirst end-face region S having little surface roughness, such securingcan achieve a sufficient positional accuracy without the need to carryout machine finishing. Therefore, the color selection electrode assembly101 can be obtained with a sufficient accuracy at low costs.

[0195] More specifically, when press-shearing a sheet material, a roughfracture surface appears on its end face. Thus, a shear plane and afracture surface of a press-sheared surface need to be ground bymachining by approximately several millimeters to give a smooth finish,where the color selection electrode body 2 needs to be welded.

[0196] However, as in the present embodiment, securing the colorselection electrode body 2 by welding or the like to the first end-faceregion S including a relatively flat shear drop and a shear plane ratherthan to the second end-face region B including a rough fracture surfaceallows the color selection electrode body 2 to be secured and supportedwith a sufficient positional accuracy without machine finishing.

[0197] As a sheet material for components including the first supportparts 112, a dual phase stainless steel or precipitation hardeningstainless steel is preferably used, for example. This is because, whenshearing these sheet materials, a relatively flat surface close to acleavage plane can be obtained as a shear plane.

[0198] As a method of welding avoiding the second end-face region Bincluding a fracture surface, shearing is conducted such that the shearplane and shear drop are on the outer side of the frame 103, and whenpressing the pair of first frames 110 in the direction that theyapproach each other, the color selection electrode body 2 is held by itsperiphery and is pulled toward the second support parts 114 with the oneside edge 112 a of the first support part 112 inclined toward the insideof the frame 103. Then, the color selection electrode body 2 is pressedagainst the first end-face region S. In this state, bringing the weldingelectrode 175 of a cylindrical cross-sectional shape into contact withthe contact portion between the color selection electrode body 2 and thefirst end-face region S from on top of the color selection electrodebody 2, the color selection electrode body 2 can be stably welded to thefirst end-face region S avoiding the second end-face region B.

[0199] Further, in the present embodiment, when the first frames 110 andsecond frames 20 are assembled to form a frame and the respective endsare joined together, it is preferable that welding strain should besmall and the amount of distortion of the stretched surface should liewithin a predetermined allowable range. Here, the amount of distortionis defined by the difference in height between a reference plane decidedby arbitrary three of four corners of the color selection electrode body2 and the remaining one of the four corners. This is achieved by, forexample, employing laser welding for welding which will be describedlater the respective components and frame 103.

[0200] The description of the present embodiment is applicable to theother preferred embodiments.

[0201] Twelfth Preferred Embodiment

[0202]FIG. 22 is a sectional view of an essential part of a colorselection electrode assembly 101M according to a twelfth preferredembodiment of the invention. In FIG. 22, a first frame 110M is in aposition indicated by broken lines before supporting the color selectionelectrode body 2 and is moved to a position indicated by solid lineswhen supporting the color selection electrode body 2. Components similarto those of the color selection electrode assembly 101 according to thesecond preferred embodiment are represented by the same referencecharacters, explanation of which is thus omitted here, and dissimilarpoints will be described particularly.

[0203] In the color selection electrode assembly 101M according to thepresent embodiment, a first support part 112M and a second support part114 in the first frame 110M which corresponds to the first frame 110makes an angle α greater than 90°.

[0204] In the state which the color selection electrode body 2 issecured to one side edge 112Ma of the first support part 112M of thefirst frame 110M, the first frame 110M is displaced toward the inside ofa frame 103M under the tension of the color selection electrode body 2(indicated by a hollow arrow in FIG. 22).

[0205]FIG. 23 shows a comparative example in which the first supportpart 112 and second support part 114 of the first frame 110 makesubstantially the right angle.

[0206] In FIGS. 22 and 23, in the state which the color selectionelectrode assemblies 101 and 101M are mounted on a CRT 180M, an orbit184M of electron beams scanning at the edge of a phosphor surface 182Mis as shown in FIGS. 22 and 23. The distance between a position P atwhich the orbit 184M passes through the color selection electrode body 2and the one side edge 112 a of the first support part 112 in the firstframe 110 and the distance between the position P and the one side edge112Ma of the first support part 112M in the first frame 110M shall bedefined as δY.

[0207] In FIG. 23 showing a comparative example, the tension of thecolor selection electrode body 2 causes the one side edge 112 a of thefirst support part 112 to be inclined toward the inside of the frame103, causing the distance δY to be relatively small.

[0208] On the other hand, in FIG. 22 according to the presentembodiment, the first support part 112M and second support part 114 makethe angle α greater than 90°, allowing the distance δY to be relativelygreat even when the one side edge 112Ma of the first support part 112Mis displaced toward the inside of the frame 113M under the tension ofthe color selection electrode body 2. Therefore, even when wrinkles dueto thermal strain at the weld between the color selection electrode body2 and first support part 112M occur at the periphery of the colorselection electrode body 2, such wrinkles due to thermal strain are notlikely to occur in a region of the color selection electrode body 2 thatcontributes to display of the CRT. Thus, the color selection electrodebody 2 is not likely to be influenced by wrinkles and the like due tothermal strain at the weld, allowing a manufacture margin to beincreased. Further, from a different point of view, the region whereelectron beam holes are formed on the color selection electrode body 2can be widened, allowing the screen size of the phosphor surface 182M tobe widened, which is advantageous in terms of a design margin for a CRT.

[0209] The description of the present embodiment is applicable to theother preferred embodiments.

[0210] Thirteenth Preferred Embodiment

[0211] A thirteenth preferred embodiment is directed to a joiningtechnique of sheet materials which is applicable to the above-describedpreferred embodiments. This technique is applied, for example, to theconnected portions between the first frames 10 and second frames 20(e.g., the welds between each flange 16 f and first support part 12) inthe first preferred embodiment.

[0212]FIGS. 24A illustrates a sectional structure of a fusion zone 206after overlapping steel sheets 202 and 204 to which laser beam isradiated in the direction indicated by a hollow arrow.

[0213]FIG. 24B illustrates a sectional structure of a fusion zone 216after radiating laser beam to the corner between steel sheets 212 and214 overlapped with each other in the direction indicated by a hollowarrow. In the respective drawings, the dimension W is the width of thefusion zone 206 or 216 as viewed in the direction in which laser beam isradiated, and the dimension G is a clearance between the steel sheets202 and 204 or that between the steel sheets 212 and 214.

[0214] Test pieces having a thickness ranging from 0.7 to 1.8 mm weresubjected to laser welding under the condition which the clearance G wasequal to or below one-tenth of the sheet thickness while varying theweld length as 10, 20 and 30 mm. Then, it was found out that, providedthat the width W of the fusion zone 206 or 216 (hereinafter alsoreferred to as fusion width) was not greater than 2 mm, two overlappedsheets remaining flat after welding without causing warps could beobtained.

[0215] Further, under such welding condition of fusion width that causesno warp, welding was carried out for the first frames 10 and secondframes 20, respectively, and for assembling the first and second frames10 and 20 into a rectangular frame, while the weld line at each of thewelds such as welds 5 in the color selection electrode assembly 1 shownin FIG. 1 was determined to be not greater than 30 mm. As a steel sheet,a dual phase stainless steel having a thickness of 1.2 mm was used. Inaddition, the size of the color selection electrode assembly 1 was setat a frame for a 34-inch CRT (diagonal dimension: 80 cm).

[0216] In this case, the amount of distortion at the four corners of thecolor selection electrode body 2 (i.e., the difference in height betweena reference plane decided by arbitrary three of the four corners and theremaining one) was not greater than 0.15 mm, which was good.

[0217] The same welding was also carried out for the color selectionelectrode assembly 101 shown in FIG. 2 to obtain the same results.

[0218] This shows that welding sheet materials together at weld lineshaving a fusion width not greater than 2 mm in the manufacturing of thecolor selection electrode assembly 101 can reduce warps of the sheetmaterials, allowing reduction in amount of distortion of the colorselection electrode assembly 101.

[0219] Although the example of employing laser welding has beendescribed, other welding methods may be used if attention is paid toavoid an excessive heat input.

[0220] Fourteenth Preferred Embodiment

[0221] In a fourteenth preferred embodiment, description will be made onsheet materials constituting the first frames 10, 110, 110B, 110C, 110D,10F, 110G, 110H and 110M and the second frames 20 and 20L and examplesof processing such materials, as a technique which is applicable to theabove-described preferred embodiments.

[0222] As sheet materials for these frames, a dual phase stainless steelNSS431-DP2 (a product of Nisshin Steel Co., Ltd., a 16.5%Cr-2%Nidual-phase stainless steel comprised of ferritic phase and martensiticphase) or a precipitation hardening stainless steel SUS631 (a17%Cr-7%Ni-1% Al steel) may be employed.

[0223] These steel sheet materials are improved in mechanical propertiesby heat treatment at 450 to 500° C.

[0224] Here, these steel sheet materials were subjected to heattreatment at 470° C. for 15 minutes for comparison of properties beforeand after the heat treatment. The heat treatment includes blackening,age hardening treatment and precipitation hardening heat treatment at450 to 500° C. The results are shown in table 1. TABLE 1 Mechanicalproperties NSS431 SUS631 Before heat treatment 0.2% yield strength (MPa)925 1000 Vickers hardness (Hv) 378 410 After heat treatment Hightemperature creep elongation (%) 0.5 1.0 0.2% yield strength (MPa) 11251250 Vickers hardness (Hv) 390 530 High temperature creep elongation (%)0.04 0.05

[0225] The 0.2% yield strength is defined as a load per unit crosssection that causes a 0.2% permanent elongation. The high temperaturecreep elongation is defined by a permanent elongation obtained bystretching a test piece under a stress of 350 MPa for one hour in a 500°C. atmosphere, following which the load is removed, and which isreturned to a normal temperature.

[0226] Table 1 shows that the heat treatment performed on the abovesteel sheets increases the 0.2% yield strength and Vickers hardnesswhile reducing the high temperature creep elongation, resulting inincreased hardness as well as improved mechanical strength.

[0227] Therefore, the first frames 10, 110, 110B, 110C, 110D, 10F, 110G,110H and 110M and second frames 20 and 20L are substantially formed ofone of a dual phase stainless steel comprised of ferritic phase andmartensitic phase and a precipitation hardening stainless steel, and aresubjected to at lest one of blackening, age hardening treatment andprecipitation hardening heat treatment at 450 to 500° C., so that thefollowing effects can be obtained.

[0228] That is, the increase in the 0.2% yield strength and Vickershardness is advantageous in that, in the case of manufacturing a thinnerframe, the frame resists a force applied to the one side edge of eachfirst support part (a contact pressure as indicated by Hertz's formulain the strength of materials) when supporting the color selectionelectrode body 2 under tension and a force applied to the frame bysupporting the electrode body 2 under tension.

[0229] Further, the reduction in high temperature creep elongation isadvantageous in controlling a reduction in the tension of the colorselection electrode body 2 due to creep deformation of the colorselection electrode body in a heat treatment step at 300 to 500° C. inthe manufacture of the color selection electrode assembly and CRT.

[0230] Fifteenth Preferred Embodiment

[0231] In a fifteenth preferred embodiment, description will be made onthe relationship between the color selection electrode body 2 and firstframes 10, 110, 110B, 110C, 110D, 10F, 110G, 110H or 110M in terms ofthermal expansion coefficient, as a technique which is applicable to theabove-described preferred embodiments.

[0232] It is preferable that the difference in thermal expansioncoefficient between the color selection electrode body 2 and firstframes 10, 110, 110B, 110C, 110D, 10F, 110G, 110H or 110M intemperatures ranging from a normal temperature to 500° C. should bewithin 10%. Here, a normal temperature is defined as 15 to 20° C.

[0233] A thermal expansion coefficient is adjusted by appropriatelychanging the shapes and selecting the materials of the color selectionelectrode body 2 and first frames 10, 110, 110B, 110C, 110D, 10F, 110G,110H or 110M.

[0234] Controlling the difference in thermal expansion coefficient to bewithin 10% as described above can prevent wrinkles in the colorselection electrode body 2 resulting from the difference in the amountof thermal expansion (or contract) between the one side edge 12 a or 112a of the first support part 12 or 112 in the first frames 10, 110, 110B,110C, 110D, 10F, 110G, 110H or 110M and the color selection electrodebody 2 joined intermittently along the extending direction of the oneside edge 12 a or 112 a.

[0235] Sixteenth Preferred Embodiment

[0236] In a sixteenth preferred embodiment, a method of manufacturing acolor selection electrode assembly will be described.

[0237]FIG. 25 is a flow chart of manufacturing steps of a colorselection electrode assembly. Although this flow chart shows steps ofmanufacturing the color selection electrode assembly 101 according tothe second preferred embodiment, the color selection electrode assembly101 according to the other preferred embodiments is also manufacturedbasically through the same steps.

[0238] The steps of manufacturing the color selection electrode assembly101 includes the steps of: (a) pressing a sheet material to form thepair of first frames 110 and pair of second frames 20; (b) joining thepair of first frames 110 and pair of second frames 20 into a rectangularframe; and (c) securing the color selection electrode body 2 to the pairof first frames 110 while pressing the side faces of the pair of firstframes 110 in the direction that they approach each other, andthereafter releasing the pressure imposed on the pair of first frames110.

[0239] The step (a) includes the steps of forming the first frames 110and forming the second frames 20.

[0240] In the step of forming the first frames 110, first, portions of apredetermined outline are punched from a parent sheet material bypressing, to form the projections 30. Next, the frame bodies 111 areformed by predetermined pressing such as bending the sheet material intoa substantially L shape, and the components are subjected to degreasingcleaning. Separately, portions of a predetermined outline are punchedfrom a parent sheet material by pressing, and are subjected topredetermined bending press, to form the third support parts 116, whichare then subjected to degreasing cleaning. Then, the third support parts116 are joined to the corresponding frame bodies 111, respectively, bylaser welding or the like. The first frames 110 are thereby formed.

[0241] On the other hand, in the step of forming the second frames 20,first, portions of a predetermined outline are punched from a parentsheet material by pressing, and are subjected to predetermined bendingpress, to form the frame bodies 22, which are then degreased.Separately, portions of a predetermined outline are punched from aparent sheet material by pressing to form the covers 24, which are thendegreased. Then, the covers 24 are joined to the frame bodies 22,respectively, by laser welding or the like. The second frames 20 arethereby formed.

[0242] In the step (b), the first frames 110 and second frames 20 areassembled into a rectangular frame and respective corners are joinedtogether by laser welding or the like. Thereafter, the connectingmembers 170K or holding members 55E are joined by laser welding or thelike, as necessary.

[0243] In the step (c), the color selection electrode body 2 is securedto the pair of first frames 110 by seam welding or the like while theside surfaces of the pair of first frames 110 are pressed in thedirection that they approach each other. Thereafter, the pressureimposed on the pair of first frames 110 is released, whereby the colorselection electrode body 2 is securely supported by the pair of firstframes 110 under tension.

[0244] The outer periphery of the color selection electrode body 2 isthereafter removed. In this way, the color selection electrode assembly101 is manufactured.

[0245] The color selection electrode assembly 101 is subjected toblackening at 450 to 500° C. and welding for joining apin-fit-hole-opened sheet to which pins provided in a CRT panel arefitted to the holding members or the like. The color selection electrodeassembly 101 is incorporated in a CRT, and the CRT is manufactured.

[0246] The basic steps of manufacturing the color selection electrodeassembly 101 are as described above.

[0247] Preferably, a heat treatment step of heating the first frames 110and second frames 20 at 450 to 500° C. is performed after pressing sheetmaterials in the step (a) and before the step (c).

[0248] That is, one heat treatment step of heating the first and secondframes 110 and 20 at 450 to 500° C. is preferably performed afterpressing sheet materials and before pressing the first frames 110 forsecuring the color selection electrode body 2 thereto.

[0249] In the flow chart shown in FIG. 25, such heat treatment step ispreferably performed in any one of steps surrounded by dash-dot lines.

[0250] As a parent sheet material, it is preferable to employ a steelsheet formed of a dual phase stainless steel or precipitation hardeningstainless steel as described in the fourteenth preferred embodiment.

[0251] That is, undergoing a heat treatment step at 450 to 500° C., asteel formed of a dual phase stainless steel or precipitation hardeningstainless steel is improved in mechanical strength. Therefore, pressinginvolving punching of a predeterminedly shaped portions and drawing suchas bending or forming projections is performed before the heattreatment, whereby press productivity is improved. Then, the heattreatment is performed after pressing, which allows the frame to berigidified.

[0252] To improve the weldability in welding the color selectionelectrode body 2 to the frame, the heat treatment is preferablyperformed in an unoxidized environment such as vacuum or nitrogen gasenvironment.

[0253] Example

[0254] An example of applying the color selection electrode assembly 1described in the first preferred embodiment to a 34-inch CRT will bedescribed hereinbelow.

[0255] As a frame material for the first frames 10 and second frames 20,a dual phase stainless steel NSS431-DP2 of 1.2 mm thickness (a productof Nisshin Steel Co., Ltd., a 16.5%Cr-2%Ni stainless steel comprised offerritic phase and martensitic phase) was employed.

[0256] The projections 30 were formed in the shape shown in FIG. 3Ahaving a width W of 6 mm, a height H of 3 mm and projecting dimension Dof 1.2 mm. Here, nine projections 30 are provided with appropriatespacing along the longitudinal direction of the first support part 12,as shown in FIG. 1. Then, an overlapped region between the flange 16 fof each of the third support parts 16 and the bottom of each of theprojections 30 on each of the first support parts 12 was welded by CO₂laser welding. The welds 5 were generated intermittently along theextending direction of the overlapped region. The welds 5 each had aweld length of 5 mm and a weld pitch of 100 mm. However, the welds 5 atthe both ends of the overlapped region each had a weld length of 20 mm.

[0257] Laser was radiated from the side of the flange 16 f of each ofthe third support parts 16 with an output of 2500 W and a pulse wave ofwelding speed of 2 m/min. In this case, the fusion zone had a width of 1to 1.5 mm and such a depth that reached the outer surface of each of thefirst support parts 12 on the opposite side of laser radiation, whichmeans fusion sufficiently occurred.

[0258] The first frames 10 and second frames 20 were also joinedtogether by laser welding at continuous welds of a rectangular shape atthe overlapped portions of the first frames 10 and second frames 20 andwelds at fillet welds between the first frames 10 and second frames 20.

[0259] Laser radiation was carried out through the openings of the bothend portions on the rear side of each of the second frames 20.Therefore, the covers 24 were joined to the second frames 20,respectively, so that the openings were formed on the both end portionsof each of the second frames 20 on the rear side.

[0260] Welding here was carried out with an output of 2500 W and acontinuous wave of a welding speed of 1 m/min. In this case, the fusionzone had a width of 1.5 to 2 mm and extended from the second supportpart 14 of the bottom of each of the first frames 10 to reach the insideof each of the second frames 20.

[0261] The color selection electrode body 2 formed of a low-carboncold-rolled steel of 0.13 mm thickness was supported by the frame 3 ofsuch structure under tension. For the color selection electrode body 2,the color selection electrode body 2C with the electron beam holes 2 aas shown in FIG. 2C was used. When supported under tension, the colorselection electrode body 2 was placed under a tension havingdistributions of 10-40 N/mm (total load of 12000 N) along thelongitudinal direction of the first frames 10.

[0262] Then, the predetermined holding members 55E were attached to thethree corners of the frame 3, and the color selection electrode assembly1 was incorporated into a CRT, which was thereafter mounted to atelevision set.

[0263] This allowed a good CRT to be obtained without problemsconcerning screen vibrations (vibrations of the color selectionelectrode body 2) due to vibrations of speaker sound. The frame 3 was 2kg in weight in this case.

[0264] For a comparative example with a conventional structure, thestructure described in the first preferred embodiment was formed to bein conformity with a conventional structure where the first frames 10are not provided with the projections 30. In this case, to withstand aload created by the same tension as mentioned above, the first frames 10needs to be welded over the entire length, and the first frames 10 andthe like needs to be of 1.8 mm thickness. Therefore, the frame 3 was 3kg in weight.

[0265] The present example and comparative example show that the weightof the frame 3 was reduced from about 3 kg in the conventional structureto about 2 kg, allowing significant weight reduction.

[0266] It has been confirmed that the color selection electrode assembly1 with the frame 3 formed as described above employing a precipitationhardening stainless steel SUS631 (17%Cr-7%Ni-1%Al steel) provides apredetermined performance.

[0267] While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A frame for a color selection electrode assemblyfor supporting a color selection electrode body under tension,comprising at least two support parts joined together at a predeterminedangle, wherein at least one projection having a convex surface and atleast one shear plane is formed on one of said support parts, and anedge of the other one of said support parts is arranged to be in contactwith a main surface of said one of said support parts and said shearplane.
 2. A frame for a color selection electrode assembly forsupporting a color selection electrode body under tension, comprising: apair of first frames; and a pair of second frames for holding said pairof first frames substantially in parallel to each other with apredetermined space therebetween, wherein said pair of first frames areeach formed in a substantially triangular sectional shape, eachincluding a first support part having one side edge to which said colorselection electrode body is secured, a second support part having oneside edge connected to the other side edge of said first support partthrough a bend, and a third support part having one side edge connectedto the other side edge of said second support part through a bend, andat least one projection having a convex surface and at least one shearplane is formed in an inner position of the one side edge of said firstsupport part, and the other side edge of said third support part isarranged to be in contact with a main surface of said first support partand said shear plane.
 3. The frame according to claim 2, wherein whenthere is no load created by tension of said color selection electrodebody, said first support part is curved arcuately to expand in adirection opposite to a direction that the tension of said colorselection electrode body works.
 4. The frame according to claim 2,wherein a holding member is attached to each of said pair of firstframes, said holding member including a curved holding part along theoutline of said bend between said first and second support parts and aholding part along the outline of said bend between said second andthird support parts.
 5. The frame according to claim 2, wherein at leastend portions of said first and second support parts are mechanicallystronger than the middle portions thereof.
 6. The frame according toclaim 2, wherein said third support part has a bead formed thereonextending in the widthwise direction thereof.
 7. The frame according toclaim 2, wherein a sheet-like reinforcing member is provided for saidthird support part, said reinforcing member being substantiallyperpendicular to said third support part and extending along thewidthwise direction of said third support part.
 8. The frame accordingto claim 2, wherein a connecting member is provided at each of connectedportions between said pair of first frames and said pair of secondframes for supporting connection.
 9. The frame according to claim 2,wherein said first support part and said second support part make anangle greater than 90 degrees.
 10. The frame according to claim 2,wherein said pair of second frames are formed by bending, and at leastone of an extending direction of said bend of each of said pair of firstframes and that of said bend of each of said pair of second frames issubstantially perpendicular to a rolling direction of a parent sheetmaterial for said pair of first frames and said pair of second frames.11. The frame according to claim 2, wherein a connected portion betweensheet materials include a weld line having a fusion width equal to orsmaller than 2 mm.
 12. The frame according to claim 2, wherein at leastone of said pair of first frames and said pair of second frames isformed of one of a dual phase stainless steel substantially comprised offerritic phase and martensitic phase and a precipitation hardeningstainless steel, and is subjected to at least one of blackening, agehardening treatment and precipitation hardening heat treatment attemperatures ranging from 450 to 500° C.
 13. The frame according toclaim 2, wherein the one side edge of said first support part has ashear drop, a shear plane and a fracture surface created bypress-shearing, said shear drop and said shear plane being provided onan outer side of said first support part with respect to said fracturesurface, and said color selection electrode body is securely supportedat said shear drop and said shear plane.
 14. The frame according toclaim 2, wherein a thermal expansion coefficient of said pair of firstframes under a temperature condition ranging from a normal temperatureto 500° C. is defined in such a range that a difference from a thermalexpansion coefficient of said color selection electrode body under saidtemperature condition is within 10%.
 15. A frame for a color selectionelectrode assembly for supporting a color selection electrode body undertension, comprising: a pair of first frames; and a pair of second framesfor holding said pair of first frames substantially in parallel to eachother with a predetermined space therebetween, wherein said pair offirst frames are each formed in a substantially triangular sectionalshape, each including a frame body in a substantially L-sectional shapehaving a first support part having one side edge to which said colorselection electrode body is secured and a second support part having oneside edge connected to the other side edge of said first support partthrough a bend, and a third support part for covering an open side ofsaid frame body opposite to said bend, at least one first projectionhaving a convex surface and at least one shear plane is formed in aninner position of the one side edge of said first support part, while atleast one second projection having a convex surface and at least oneshear plane is formed in an inner position of the other side edge ofsaid second support part, and the one side edge of said third supportpart is arranged to be in contact with a main surface of said secondsupport part and said shear plane of said second projection, while theother side edge of said third support part is arranged to be in contactwith a main surface of said first support part and said shear plane ofsaid first projection.
 16. The frame according to claim 15, wherein atleast part of said third support part is mechanically stronger than saidfirst and second support parts.
 17. The frame according to claim 15,wherein said second support part is wider at end portions thereof thanat a middle portion thereof.
 18. The frame according to claim 15,wherein said third support part has a bead formed thereon extending inthe widthwise direction thereof.
 19. The frame according to claim 15,wherein a connecting member is provided at each of connected portionsbetween said pair of first frames and said pair of second frames forsupporting connection.
 20. The frame according to claim 15, wherein atleast one of said pair of first frames and said pair of second frames isformed of one of a dual phase stainless steel substantially comprised offerritic phase and martensitic phase and a precipitation hardeningstainless steel, and is subjected to at least one of blackening, agehardening treatment and precipitation hardening heat treatment attemperatures ranging from 450 to 500° C.
 21. A method of manufacturing acolor selection electrode assembly, comprising the steps of: (a) forminga pair of first frames and a pair of second frames by pressing a sheetmaterial; (b) joining said pair of first frames and said pair of secondframes to form a rectangular frame; (c) securing a color selectionelectrode body to said pair of first frames while pressing side faces ofsaid pair of first frames in the direction that they approach eachother, and thereafter releasing a pressure imposed on said pair of firstframes; and (d) performing heat treatment for heating said pair of firstframes and said pair of second frames at temperatures ranging from 450to 500° C. after pressing in said step (a) and before said step (c).